Retaining mechanism

ABSTRACT

A retaining mechanism for use in affixing a stratum to bone is disclosed. The retaining mechanism comprises a stratum, a retaining element and a spring element. The stratum comprising a first surface, a second surface, and a hole extending between the first surface and the second surface, wherein the second surface is configured to engage at least a portion of the bone. The retaining element comprises a first position that permits a fastener to be passed through the hole, and a second position that at least partially overlaps the hole. The spring element is configured to engage the stratum and configured to engage the retaining element such that the spring element helps maintain the retaining element in its second position so as to help prevent inadvertent backing out of the fastener after the fastener has been fully inserted into the hole.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of application Ser. No. 12/970,130,filed on Dec. 16, 2010, now allowed. The contents of this priorapplication is herein incorporated by reference in its entirety.

FIELD OF INVENTION

The present invention is directed to systems for affixing a stratum tobone.

BACKGROUND

The present disclosure relates to retaining mechanisms, and moreparticularly, systems for affixing a stratum to bone.

SUMMARY OF THE INVENTION

A retaining mechanism for use in affixing a stratum to bone isdisclosed. The retaining mechanism comprises a stratum, a retainingelement and a spring element. The stratum comprising a first surface, asecond surface, and a hole extending between the first surface and thesecond surface, wherein the second surface is configured to engage atleast a portion of the bone. The retaining element comprises a firstposition that permits a fastener to be passed through the hole, and asecond position that at least partially overlaps the hole. The springelement is configured to engage the stratum and configured to engage theretaining element such that the spring element helps maintain theretaining element in its second position so as to help preventinadvertent backing out of the fastener after the fastener has beenfully inserted into the hole.

Further, a system for affixing stratum to bone is disclosed. The systemcomprises a retaining mechanism and at least one fastener configured topass through the hole in the stratum and engage the bone.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric top view of a retaining mechanism for affixing astratum to bone;

FIG. 2 is a cut-away, exploded, isometric top view of retainingmechanism of FIG. 1;

FIG. 3 is a cut-away, isometric top view of the retaining mechanism ofFIG. 1;

FIG. 4 is a cut-away, isometric bottom view of the retaining mechanismof FIG. 1;

FIG. 5 is an isometric top view of the retaining element of FIG. 1;

FIG. 6 is a cut-away, isometric top view of the stratum of FIG. 1;

FIG. 7 is a cut-away, isometric top view of the retaining mechanism ofFIG. 1;

FIG. 8 is another cut-away, isometric top view of the retainingmechanism of FIG. 1;

FIG. 9 is a cut-away, isometric top view of a system for affixing thestratum of FIG. 1 to bone; and

FIG. 10 is a view of the system of FIG. 9 when the retaining element isin its second position.

DETAILED DESCRIPTION

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments, or examples,illustrated in the drawings and specific language will be used todescribe the same. It will nevertheless be understood that no limitationof the scope of the invention is thereby intended. Any alterations andfurther modifications in the described embodiments, and any furtherapplications of the principles of the invention as described herein arecontemplated as would normally occur to one skilled in the art to whichthe invention relates.

FIG. 1 shows an isometric top view of a retaining mechanism 100 foraffixing a stratum 20 to bone, for example, to two or more levels ofvertebral bodies. As shown in FIG. 1, the stratum 100 is designed forconnecting three vertebral bodies (not shown), each vertebral bodyreceiving two fasteners, one fastener through each hole, for example,holes 22 and 22A. As shown in FIG. 1, the stratum 20 may be, forexample, a spinal plate for connecting cervical vertebrae by affixingthe stratum 20 to the anterior surface of the vertebrae. Further, asshown in the Figures and as described herein, the fasteners may be, forexample, screws.

The retaining mechanism 100 comprises a stratum 20, a retaining element60 and a spring element 30. The stratum 20 comprises a first surface 19,a second surface 21, and six holes (for example, holes 22 and 22A)extending between the first surface 19 and the second surface 21. Asshown in FIG. 1, the first surface 19 is configured to engage at least aportion of the bone. The retaining element 60 comprises a first positionthat permits a fastener to be passed through the hole (for example, hole22 or 22A), a second position that at least partially overlaps the hole(for example, hole 22 or 22A), and a spring element 30 configured toengage the stratum 20 and configured to engage the retaining element 60such that the spring element 30 helps maintain the retaining element 60in its second position so as to help prevent inadvertent backing out ofthe fastener after the fastener has been fully inserted into the hole(for example, hole 22 or 22A). Note that, as shown in FIG. 1, thestratum contains three retaining mechanisms. One is retaining mechanism100 and the other two are similar, with each mechanism configured foranother bone or bone segment, for example, configured for separatevertebral bodies.

FIG. 2 shows a cut-away, exploded, isometric top view of retainingmechanism 100 of FIG. 1. As shown in FIG. 2, the stratum 20 is furtherconfigured to engage the retaining element 60. As shown in FIG. 2, thesecond surface 21 of the stratum 20 comprises a first recess 24configured to engage the retaining element 60. Further, as shown in FIG.2, the first recess 24 comprises a second recess 26 configured to engagethe spring element 30.

In addition, as shown in FIG. 2, the retaining element 60 furthercomprises a tab 62 and the stratum 20 further comprises a channel 50. Asshown in FIG. 2, the tab 62 extends away from a center of the retainingelement 60. Further, as shown in FIG. 2, the first recess 24 comprises asidewall 25 and the sidewall 25 comprises the channel 50. Morespecifically, as shown in FIG. 2, the channel 50 is what remains after asection of material is removed from the sidewall 25. As shown in FIG. 2,the channel 50 is configured to engage the tab 62 and the tab 62 isconfigured to engage the channel 50.

In addition, as shown in FIG. 2, the retaining element 60 furthercomprises a first cut-out 64 and a second cut-out 66. In addition, asshown in FIG. 2, the retaining element 60 further comprises a depression68 (shown in phantom lines) on its underside, i.e., the side facing thefirst recess 24 of the stratum 20.

FIG. 3 shows a cut-away, isometric top view of the retaining mechanism100 of FIG. 1. As shown in FIG. 3, the retaining element 60 is in itsfirst position, which permits a fastener to be passed through the hole22 or 22A. Further, as shown in FIG. 3, the depression 68 is positionedand configured to engage the spring element 30 when the retainingelement 60 is in its first position.

FIG. 4 shows a cut-away, isometric bottom view of the retainingmechanism 100 of FIG. 1. As shown in FIG. 4, the retaining element 60further comprises a grommet portion 69 situated between holes 22 and22A. The grommet portion 69 helps the retaining element 60 maintainposition affixed to the stratum 20, but also allows the retainingelement 60 to rotate, for example, between its first position and itssecond position.

FIG. 5 shows an isometric top view of the retaining element 60 ofFIG. 1. As shown in FIG. 5, the depression 68 is visible in phantomlines (as well as in other figures) because it is situated on theunderside of the retaining element 60. Further, as shown in FIG. 5, theretaining element 60 further comprises a central shaft 67 that passesthrough the stratum 20. As shown in FIG. 5, at least the top of thecentral shaft 67 has a hexagonal shape 65. Also, as shown, the centralshaft 67 defines a hole through the retaining element 60 and is situatedat or near the center of the retaining element 60. As shown, theretaining element 60 may be rotated by, for example, inserting ahexagonal-shaped end of a tool into the central shaft 67 to therebyrotate the retaining element 60 from, for example, its first position toits second position, or vice versa. Note that the central shaft 67 (andcorresponding tool) need not have a hexagonal-shape 65, but may be oneof a variety of shapes so long as the function of rotating the retainingelement 60 can be accomplished. For example, other polygonal shapes suchas a square would suffice.

FIG. 6 shows a cut-away, isometric top view of the stratum 20 of FIG. 1.FIG. 6 shows an enlarged view of the first recess 24, the second recess26, the spring element 30 and the channel 50. As shown in FIG. 6, thestratum 20 further comprises a central hole 23 configured to receive thecentral shaft 67 of the retaining element 60. Further, as shown in FIG.6, the channel 50 comprises a first end 52 and a second end 54. When theretaining element 60 is in its first position, the tab 62 is situated ator near the first end of the channel 52. When the retaining element 60is in its second position, the tab 62 is situated at or near the secondend of the channel 54.

FIG. 7 shows a cut-away, isometric top view of the retaining mechanism100 of FIG. 1. Specifically, FIG. 7 shows an enlarged view of the areasurrounding the retaining element 60 when it is in its first position.As shown in FIG. 7, when the retaining element 60 is in its firstposition, the first cut-out 64 and the second cut-out 66 of theretaining element 60 permit first and second fasteners to be passedthrough the first and second holes 22 and 22A of the stratum 20,respectively. Further, as shown in FIG. 7, when the retaining element 60is in its first position, the depression 68 on the underside of theretaining element 60 engages the spring element 30. In this way,depression 68 is intended to at least partially relieve forces exertedon the spring element 30 when the retaining element 60 is in its firstposition.

FIG. 8 shows another cut-away, isometric top view of the retainingmechanism 100 of FIG. 1. Specifically, FIG. 8 shows an enlarged view ofthe area surrounding the retaining element 60 when it is in its secondposition. As shown in FIG. 8, the retaining element 60 further comprisesa first blocking portion 61 and a second blocking portion 63. The firstcut-out 64 is situated between the first blocking portion 61 and thesecond blocking portion 63, and the second cut-out 66 is situatedopposite the first cut-out 64, and similarly, between the first blockingportion 61 and the second blocking portion 63. As shown in FIG. 8, thewhen the retaining element 60 is in its second position, the firstblocking portion 61 and the second blocking portion 63 of the retainingelement 60 partially overlap the first and second holes 22 and 22A ofthe stratum 20, respectively, so as to prevent inadvertent backing outof fasteners after they have been fully inserted into the first andsecond holes 22 and 22A. Further, as shown in FIG. 8, when the retainingelement 60 is in its second position, the first cut-out 64 engages thespring element 30 so as to help maintain the retaining element 60 in itssecond position. When the retaining element 60 is in its secondposition, the spring element 30 is less stressed than when the retainingelement 60 rotates between its first and second positions, but appliesenough pressure against the first cut-out 64 to help maintain theretaining element 60 in its second position.

FIG. 9 shows a cut-away, isometric top view of a system for affixing thestratum 20 of FIG. 1 to bone. As shown in FIG. 9, system comprises theretaining mechanism 100 and a fastener 40 configured to pass through thehole 22 and engage the bone. Specifically, FIG. 9 shows an enlarged viewof the area surrounding the retaining element 60 when it is in its firstposition. As shown in FIG. 9, when the retaining element 60 is in itsfirst position, the first cut-out 64 and the second cut-out 66 of theretaining element 60 permit the first fastener 40 and a second fastenerto be passed through the first and second holes 22 and 22A of thestratum 20, respectively. Further, as shown in FIG. 9, when theretaining element 60 is in its first position, the depression 68 on theunderside of the retaining element 60 engages the spring element 30.

FIG. 10 shows a view of the system of FIG. 9 when the retaining element60 is in its second position. As shown in FIG. 10, fastener 40 has beenfully inserted into hole 22 of stratum 20. Accordingly, the firstblocking portion 61 partially overlaps the first hole 22 and therebypartially covers the head of the fastener 40 so as to preventinadvertent backing out of the fastener 40. Further, as shown in FIG.10, when the retaining element 60 is in its second position, the firstcut-out 64 engages the spring element 30 so as to help maintain theretaining element 60 in its second position.

Parts of the retaining mechanism 100 may have a variety of shapes andsizes and still accomplish the functions described herein. For example,as shown, although the spring element 30 has a rectangular shape, avariety of shapes may be employed. For example, a more arcuate shape maybe employed. Further, a different shape and/or type of spring than thatshown may be employed. That is, as the spring element 30 shown may beconsidered a type of leaf spring, another type of spring having adifferent shape may be used.

Similarly, the shape of the retaining element 60 or any of itsconstituent parts may be different than that shown in the Figures aslong as they accomplish their respective functions described herein. Theretaining element 60 may any shape as long as it allows for insertion offasteners and helps prevent inadvertent backing out of the fastenersafter the fasteners have been fully inserted into the holes (forexample, hole 22 or 22A). Further, although the tab 62 is shown ashaving a rectangular shape, a variety of shapes may be employed. As yetanother example, although the depression 68 is shown as having a conicalshape, a variety of shapes—for example, a spherical shape—may beemployed.

In the embodiments shown and described herein, the retaining element 60is substantially rigid. Further, in the embodiments shown and describedherein, the stratum 20 is substantially rigid; accordingly, the channel50 therein is substantially rigid.

The term “substantially” as used herein may be applied to modify anyquantitative representation which could permissibly vary withoutresulting in a change in the basic function to which it is related. Forexample, the retaining element 60 may be considered substantially rigidif when the retaining element 60 is in its second position, theretaining element 60 at least partially overlaps a hole 22 or 22A so asto help prevent inadvertent backing out of a fastener after the fastenerhas been fully inserted into the hole.

In the embodiments described herein, the stratum may be made of avariety of biocompatible materials (metal or non-metal), including butnot limited to, Titanium Alloys, commercially available Titanium,stainless steel, polyetheretherketone (“PEEK”), cobalt chrome (“CoCr”),polyetherketoneketone (“PEKK”), ultra high molecular weight polyethylene(“UHMWPE”), polyethylene, shape memory metals, other polymers or anycombination of such materials. Similarly, the retaining mechanism 60and/or the fasteners (for example, fastener 40) may be made of the samematerials. Also, any suitable materials know in the art may work foreach of these elements as well as for other elements described herein.

In the embodiments shown, the spring element 30 has elastic properties.Thus, the spring element 30 comprises a material that has elasticproperties. For example, the spring element 30 may comprise a materialsuch as metal that is elastic. In addition, the spring element 30, forexample, may be made of Nickel Titanium (NiTi), commercially pureTitanium, a Titanium alloy or any combination of such materials.Further, as noted, the spring element 30 may have shapes other thanrectangular. That is, the spring element 30 may take any form thatsatisfies its function described herein, for example, being able toadequately engage with the retaining element 60 and the stratum 20 andbeing able to sufficiently maintain the retaining element 60 in itssecond position so as to not allow the fasteners (for example, fastener40) to inadvertently back out of the stratum 20.

All adjustments and alternatives described above are intended to beincluded within the scope of the invention, as defined exclusively inthe following claims. Those skilled in the art also should realize thatsuch modifications and equivalent constructions or methods do not departfrom the spirit and scope of the present disclosure, and that they maymake various changes, substitutions, and alterations herein withoutdeparting from the spirit and scope of the present disclosure.Furthermore, as used herein, the terms components and modules may beinterchanged. It is understood that all spatial references, such as“superior,” “inferior,” “anterior,” “posterior,” “outer,” “inner,”“upper,” “underside,” “top,” “bottom,” and “perimeter” are forillustrative purposes only and can be varied within the scope of thedisclosure.

The invention claimed is:
 1. A retaining mechanism for use in affixing astratum to bone, the mechanism comprising: a stratum comprising a firstsurface, a second surface, and a hole extending between the firstsurface and the second surface, the hole having a central longitudinalaxis that extends substantially perpendicular to the first surface andthe second surface, wherein the second surface is configured to engageat least a portion of the bone; a retaining element comprising: a firstposition that permits a fastener to be passed through the hole, and asecond position that at least partially overlaps the hole, the retainingelement being configured to rotate from the first position to the secondposition; and a spring element configured to engage the stratum and theretaining element such that the spring element maintains the retainingelement in its second position so as to prevent inadvertent backing outof the fastener after the fastener has been fully inserted into thehole.
 2. The mechanism of claim 1, wherein the stratum is furtherconfigured to engage the retaining element.
 3. The mechanism of claim 1,wherein the spring element has a substantially linear configuration. 4.The mechanism of claim 1, wherein the stratum is substantially rigid. 5.The mechanism of claim 1, wherein the first surface of the stratumcomprises a first recess configured to engage the retaining element. 6.The mechanism of claim 5, wherein the first recess comprises a secondrecess configured for disposal of the spring element.
 7. The mechanismof claim 1, wherein: the retaining element further comprises a first legand a second leg such that when the retaining element is in its secondposition, a portion of the first leg or a portion of the second legpartially overlaps the hole.
 8. A system for affixing a stratum to bone,the system comprising: the retaining mechanism recited in claim 1; and afastener configured to pass through the hole and engage the bone.
 9. Themechanism of claim 1, wherein the spring element comprises materialhaving elastic properties.
 10. The mechanism of claim 1, wherein thespring element comprises Nickel Titanium or other Titanium alloy. 11.The mechanism of claim 1, wherein the retaining element comprises acentral shaft configured to pass through a central hole in the stratum,the central shaft situated at or near a center of the retaining element,the retaining element comprising a tab and the stratum comprising achannel, the tab being movably disposed in the channel such that theretaining element is in its first position when the tab is positionedadjacent a first end of the channel and the retaining element is in itssecond position when the tab is positioned adjacent a second end of thechannel.
 12. The mechanism of claim 11, wherein the tab is spaced apartfrom the central shaft.
 13. The mechanism of claim 1, wherein a firstrecess configured to engage the retaining element extends into the firstsurface, the first recess comprising a second recess configured fordisposal of the spring element, the second recess extending into thefirst recess without extending through the second surface.
 14. Aretaining mechanism for use in affixing a stratum to bone, the mechanismcomprising: a stratum comprising a first surface, a second surface, anda hole extending between the first surface and the second surface, thesecond surface situated in a first plane, wherein the second surface isconfigured to engage at least a portion of the bone, and a retainingelement comprising: a first position that permits a fastener to bepassed through the hole; and a second position that at least partiallyoverlaps the hole, the retaining element being configured to rotate fromthe first position to the second position; and a spring elementconfigured to engage the stratum and the retaining element such that thespring element maintains the retaining element in its second position soas to prevent inadvertent backing out of the fastener after the fastenerhas been fully inserted into the hole.
 15. The mechanism of claim 14,wherein the retaining element comprises a central shaft configured topass through a central hole in the stratum, the central shaft situatedat or near a center of the retaining element, the retaining elementfurther comprising a tab that is spaced apart from the central shaft,the stratum comprising a channel, the tab being movably disposed in thechannel such that the retaining element is in its first position whenthe tab is positioned adjacent a first end of the channel and theretaining element is in its second position when the tab is positionedadjacent a second end of the channel.
 16. The mechanism of claim 15,wherein the channel extends in a direction that is perpendicular to anaxis defined by the hole.
 17. A system for affixing a stratum to bone,the system comprising: the retaining mechanism recited in claim 14; anda fastener configured to pass through the hole and engage the bone. 18.The mechanism of claim 14, wherein a first recess configured to engagethe retaining element extends into the first surface, the first recesscomprising a second recess configured for disposal of the springelement, the second recess extending into the first recess withoutextending through the second surface.
 19. A retaining mechanism for usein affixing a stratum to bone, the mechanism comprising: a stratumcomprising a first surface, a second surface, and a hole extendingbetween the first surface and the second surface, wherein the firstsurface is configured to engage at least a portion of the bone and thesecond surface defines a first recess having a depth, the first recessdefining a second recess; a retaining element disposed in the firstrecess comprising: a first position that permits a fastener to be passedthrough the hole; a second position that at least partially overlaps thehole, the retaining element being configured to rotate from the firstposition to the second position; a first leg and a second leg, both legsbeing situated in a first plane; and a tab configured to engage thestratum; and a spring element disposed in the second recess configuredto engage the retaining element to maintain the retaining element in itssecond position so as to prevent inadvertent backing out of the fastenerafter the fastener has been fully inserted into the hole.
 20. Themechanism of claim 19, wherein: the stratum further comprises a centralhole extending through the first and second surfaces; and the retainingelement includes a central shaft configured for disposal in the centralhole to allow the retaining element to rotate relative to the stratumabout a longitudinal axis that extends parallel to the central hole, thecentral shaft being situated at or near a center of the retainingelement.